At the main menu, select the "Extras" option, and choose the "Enigma Codes" selection. Then, enter one of the following codes to unlock the corresponding bonus mode and achievement. Note: You must collect all the enigma code pieces for a code throughout the main missions of the game before you can enable it. Start a new game after unlocking a mode to access it. Your collectables, perks, and upgrades will remain intact, but will not progress.

Code 1

Enter the following code under "Code 1" to unlock 999 mode (Uber difficulty, 999 health, infinite ammunition) and the "Secrets Revelead I" achievement. Note: This code is obtained from all enigma code pieces starting with the numbers 1 and 8.

1: 01, 02, 03, 04, 05, 06, 07, 08, 09

8: 08, 07, 06, 05, 04, 03, 02, 01, 09

Code 2

Enter the following code under "Code 2" to unlock Walk In The Park mode (I Am Death Incarnate difficulty, HUD disabled) and the "Secrets Revelead II" achievement. Note: This code is obtained from all enigma code pieces starting with the numbers 2 and 7.

2: 02, 04, 06, 08, 01, 03, 05, 07, 09

7: 07, 05, 03, 01, 08, 06, 04, 02, 09

Code 3

Enter the following code under "Code 3" to unlock Hardcore mode (Uber diffculty, all health and armor drops disabled) and the "Secrets Revelead III" achievement. Note: This code is obtained from all enigma code pieces starting with the numbers 3 and 6.

3: 03, 06, 09, 03, 06, 09, 03, 06, 09

6: 06, 03, 09, 06, 03, 09, 06, 03, 09

Code 4

Enter the following code under "Code 4" to unlock Ironman mode (Uber difficulty, one life) and the "Secrets Revelead IV" achievement. Note: This code is obtained from all enigma code pieces starting with the numbers 4 and 5.

4: 04, 08, 03, 07, 02, 06, 01, 05, 09

5: 05, 01, 06, 02, 07, 03, 08, 04, 09

Wolfenstein 3D level

In Chapter 4, meet Anya in the Resistance secret base. After the helicopter theft, go upstairs to the top floor and search for a room with an old mattress on the floor near the window. Interact with the bed, and select the option to enter a nightmare to play a level from Wolfenstein 3D.

All collectible locations

Search the indicated locations to find all 72 enigma codes, 50 gold items, 10 letters. Note: You can search for missing collectibles through chapter select at any time during the story or after completing the game. It also does not matter if you are playing the Fergus or Wyatt timeline. The only difference between the timelines is that you can either pick locks or hack circuits, but the levels are the same and collectibles are unaffected.
Stealth killing commanders will mark some collectible locations on your map with a question mark. However, this does not reveal all collectible locations. There are areas that do not have a commander or side-quests that must be completed to get an item. As soon as you pick up a collectible, it will immediately be saved. Thus, you do not have to reach the next checkpoint for it to save the collectible. Additionally, if you start a completely new game, your collectible progress will still carry over. You can view how many collectibles you have obtained in each level under chapter select. Each collectible has its own specific name, making it easier to identify what you are missing. To see their names, open the collectibles menu during a mission.

After finding the Laser Cutter in Chapter 4, you can upgrade it into the Laser Pistol. Later in Chapter 4, you will go on the catwalks above a coal-moving vehicle below. Go down the steps to the left to collect an item that resembles the battery originally collected to charge the cutter to upgrade it.

LaserKraftwerk upgrades

The LaserKraftwerk is obtained in the London Nautica during the Resistance's attack to get Prototype Stealth Helicopters. It can be upgraded with the following features:

Entry #1: May 11, 1940. I've only been back home for three days and now the Nazis have arrived in town. They killed Jakub Brozek. He was shot in the head. His horse was blocking the road. He taught me how to French kiss. I'm going to do something about this situation.

Entry #2: May 12, 1940. The Nazis have taken over the police station. They are asking local people to volunteer for service. I'm going to volunteer. I'm going to find a way to kill them.

Entry #3: May 18, 1940. Daytime I care for the sick, working at the asylum. On the evenings, I go to town to prepare for supper for the Nazis at the police station. They seem to trust me. I think I can lure one of them away. If I can get to a Nazi alone, I think I can kill him. I have never killed anyone. I don't know how to fight or fire a weapon. I will have to be smart about it. I miss the university. Perhaps, what I'm about to do will be a learning experience.

Entry #4: June 25, 1940. The Nazi appears to have a very high opinion of his mother. I learned this as a he was bleeding to death at the end of my knife at the outhouse next to the bakery. "Mutti!", "Mutti!" he whimpered. My hands were shaking. Nearly dropped my knife. I had told him I would kiss him and he let me lead him outside. Into the night.

Entry #5: November 29, 1940. The Nazi appears to love his sausage. I learned this as he kept on eating his supper even though the cyanide must have ruined the flavor. His eyes rolled back, all white. Yet he kept chewing. The cyanide I stole from mother's cabinet. At times I am struck with pangs of remorse. But then, I think of Jakub Brozek.

Entry #6: May 2, 1941. The Nazi appears to become sleepy after climaxing. I learned this as his little soldiers were leaking out of me onto his sheets. And his face turned blue, from the rope applied to his neck in his slumber. Tomorrow is my eighteenth birthday.

Entry #7: May 29, 1941. The Nazi appears to have been brought up lazy. I've learned this when I outran three of them, carrying a crate of grenades. I think I'm pregnant. I wish I knew how to use a gun.

Entry #8: July 6, 1941. The Nazi appear to be overly devoted to his police station. I learned this while tossing grenades into the building. Seven grenades went in but not a single Nazi came out. Does killing Nazis make me a murderer? Don't know. Don't think so. I'm not a soldier, but this is what soldiers do. And I have to steel myself from emotion, like a soldier does.

Entry #9: August 9, 1941. The Nazis appears to be highly gullible. I learned this as I pretended I was drowning and he dove in to save me. Body armor and all. I had only to apply the gentlest of pressures to push him until he stopped struggling. I am pregnant. It's not showing but I think mother suspects. I've decided to find an apartment for myself.

Entry #10: August 30, 1941. I have my own apartment, two floors above the bakery. I can't leave this Nazi baby inside me anymore. It has to come out. I took some pills from my mother's cabinet. They did not work. All they did was make me sick.

Entry #11: September 3, 1941. The Nazi appears to be a reckless driver. I learned this after I cut his brake line and his car went over a cliff, as he drove down the mountain. I didn't see it happen, but there was a picture in the paper. I had a friend at the university who successfully terminated her pregnancy, through consumption of Pennyroyal oils. I have written her, for instructions.

Entry #12: September 13, 1941. A letter arrived from London today. I have presumed a vial of Pennyroyal oil. I have stolen some antibiotics from mother. I won't be coming to work tomorrow.

Entry #13: September 14, 1941. Pain unbearable. Won't stop bleeding.

Entry #14: September 20, 1941. Still alive. The Nazi baby is gone. After the weekend I go back to work. I have patients to tend to. I have Nazis to kill.

Entry #15: January 5, 1942. The Nazi appears to have poor reaction time. I learned this as I ran him over at a red light. I don't know what came over me. It was in the middle of the day and people were looking. I drove away as fast as I could. I have to reduce the rate of my attacks, or they will catch me.

Entry #16: July 9, 1943. The Nazi appears to be made of bacon. I learned this as nine of them burned alive inside a late night establishment. A lot can be accomplished with padlocks and gasoline. Father could smell the gasoline on my coat. I lied to him. He mustn't know what I have done. He's too sensitive.

Entry #17: July 4, 1944. The Nazi is a hopeless romantic. I learned this while smashing his skull, using the hammer I had hid behind my back, as he knelt to pick up my fallen glove. If I was a boy, father would have taught me how to handle a rifle. But instead I was trained to nurse the afflicted, dig dirt for relics and write papers. I wish I knew a soldier. He could teach me how not to feel remorse. He would understand me.

Entry #18: September 23, 1946. A man came in today. Horrible head trauma. He has scars all over him. He won't speak. No ones knows where he's from. I think he's a soldier, but not a Nazi. I wish he could talk to me. He has a strength about him.

Entry #19: July 10, 1948. The war is over. The Nazis have declared victory. People are celebrating the peace. I can't stop crying. For me, this war is never ending.

Entry #20: November 16, 1951. The Nazi appears to have a hot temper. I learned this as I attempted to smash his head with a flower pot I dropped from my apartment window. Sadly, I missed. He had friends nearby. They broke my door down. I said it was an accident but they gave me a black eye and spit on my dress. I want people on my side I can rely on. My grandparents are on my side. But they are not fit to fight.

Entry #21: July 17, 1955. The Nazi appears to be a choosy bachelor. I learned this as we sat on a picnic blanket in the meadow lands. He said he would kiss me, if I bleached my hair blonde. I was nauseated by his request. But as long as I smile and hide the hate, no one is suspicious of me. So he drank the wine I spiked with sedatives. And I rolled him down a shallow grave.

Entry #22: December 24, 1956. My heart is breaking. Friends I've known my whole life have all become Nazis. Mother and Father are not happy about it, but they comply rather than resist. I feign my smile and act cheerful, but I have started to resent my own parents. I am 33 years old. I am all alone in the world.

Entry #23: May 6, 1957. I should keep fighting. But who is there to fight? Everyone is a Nazi now. Or at least they pretend to be. I can no longer tell the difference.

Entry #24: August 28, 1960. Deathshead's men are coming by the asylum every other week. They are taking people that have been in my care for years. I look the other way. I hate them. I hate myself for giving up. But I can't fight alone anymore. I watch the man with the scars. I whisper things to him. Sometimes I can see some part of him awake. I wonder if he can see me. I will not let them take him. That was the last entry, William. Some of the things in this diary happened a long time ago. And some of them may have happened to me. I miss you. I missed you a long time before I met you.

Max's Missing Toys side-quest and locations

In Chapter 7, after obtaining a sample of the "Super Concrete" for Anya, Max will return to his room and go to sleep. There is a crayon drawing of Max's four missing toys near his bed. The toys are hidden in the Kreisau Circle base. After finding all of them, go back to the crayon drawing to return the toys. Successfully complete this side-quest to unlock Max's entry in the character info panel. The toys are located in the following areas:

Robot: It is on your way out of the Kreisau Circle Hangar. It can be heard near the hangar entrance.

Telephone: It is in Caroline Becker's desk.

Letter Blocks: It is inside the hidden chamber behind the poster in Caroline's bedroom. Crawl into the gap to find it to the left, on the ground.

Fire Truck: Talk to Wyatt or Fergus to get the key, open the locked door, then look on the shelf to the right of the door.

Defeating Fire Troopers

Use the shotgun when facing Fire Troopers at close range, but be careful since they will inflict a lot of damage. You should have a large amount of health and armor if attempting close combat. A few Tesla grenades and the assault rifle will work well at medium range. To take them out at long range, use the Marksman Rifle or Laser.

When playing on the Uber difficulty, try firing constant shots from the AR Marksman's automatic plasma rifle. Shoot them a few times with the LaserKraftwerk's Targeting Scope at close range to kill them. Get two direct hits with the rocket launcher to also kill a Fire Trooper.

Defeating Kampfhunds

With either the 1946 or 1960 version, kill the Kampfhund before it is alerted using a knife throw or silenced pistol shot.

Defeating the London Monitor

Start by attacking its eye, then both the eye and the missile launchers. After all the missile launchers are destroyed, the area underneath its red spot will open. Go under the London Monitor, and shoot up into its engine. Continue to shoot both its eye and engine until it has been defeated.

Defeating Rocket Troopers

Use heavy weapons, such as rockets, against Rocket Troopers. One or two shots should kill them. When playing on the Uber difficulty, use repeating shots from the AR Marksman's automatic plasma rifle.

Defeating Space Marines

Space Marines are vulnerable to Tesla grenades. You can also shoot them with an AR Marksman or MG-60 to kill them. If you can use stealth to approach them, a knife or headshot from a suppressed 1960 handgun will also work.

Defeating Supersoldaten

When facing the 1960 version, use energy weapons. Standard bullets will only inflict minimal damage on its armored parts. Try firing a fully charged LaserKraftwerk, and connect all its lasers.

Use the assault rifle in dual-wield mode with its under-slung rocket launchers to inflict significant damage.

Fire the mount machine gun if you need to save ammunition for other weapons. Charge up again when its energy gets low and repeat.

Destroying Zeppelins

Use the following strategy when facing the two Zeppelins in the last level. There are two Flak cannons mounted on the sides of the upper levels of the back. Use them to hit the cylinder tube on the bottom. One cannon cannot be used to destroy both tubes because of its limited firing radius. After they are destroyed, Deathshead cannot use his shield.

Fallout 3 reference

In Chapter 7, Anya will ask for a sample of the moldy "Super Concrete". Look to the right of the Kreisau Circle Hangar entrance, and locate the large red circular door covered in steam. It is marked with "101", referencing Vault 101 and its huge circular door in Fallout 3.

Mario series reference

Enter your hideout, and go upstairs to Max Haas' bedroom to find Power Stars plushies on his bed.

Quake 3 reference

During the opening sequence for Chapter 6: London Nautica, Bobby Bram is driving Blazkowicz to his objective in London. The keychain hanging from the ignition is a rocket launcher from Quake 3.

Easy "Bullseye" achievement

Play Chapter 3 in the Fergus timeline on the "Can I Play, Daddy?" difficulty. Progress through the first section, and make sure you have at least one grenade. Enter the gate house, and go to the left. Hot-wire the elevator to reach the top floor, which has some steel beams under the train bridge. There is a spawn point for an attack drone on the other side and a checkpoint just before it. Note: You can also find a health upgrade nearby. Take out a grenade and walk towards the other side. The flying attack drone will spawn below the walkway, on the right side. Throw the grenade at the walkway in front of you, where the drone appears. It should get stuck in the environment and kill the drone. Pause the game, restart from the last checkpoint, and repeat the process until you earn the demolition perk 4 to get the "Bullseye" achievement.

Easy "Endurance II" achievement

The in-game description states "Kill 5 enemies in 10 seconds using a detached turret", but you do not have to use an actual turret. The Super-Soldaten's chain gun also will qualify, as they are basically detached turrets.

Easy "Sentinel" achievement

You must kill five enemies with a thrown back grenade to get the "Sentinel" achievement. In Chapter 3, reach the second checkpoint (the second time you are dropped from the car) on the easiest difficulty. Stand by the door, and wait for one of the soldiers to throw a grenade at you, then grab it and throw it back. Keep restarting from the checkpoint until you manage to kill all the soldiers with the thrown back grenade to get the achievement.

Easy "Über Hero" achievement

It is easier to complete the game on the Über difficulty during a second playthrough, as you will retain your perk and weapon upgrades and know strategies to defeat various enemies and Bosses. During your playthrough, make sure to use cover. Enemies will inflict a lot of damage on the Über difficulty, but the majority of them will die quickly. Keep your distance to force enemies to miss. Use stealth, especially during the early chapters when you are at a disadvantage. You can defeat the majority of enemies by sneaking up and killing them with your knife or pistol; or simply ignore enemies altogether. Try unlocking as many perks as possible as you progress, as they give nice advantages. Rely heavily on the LKW (and Laser Marksman when obtained) in areas where you can recharge. The LKW can destroy the large robots with one or two shots after upgraded. Always aim for the head. You can kill normal soldiers with a few headshots. Use grenades in areas where enemies attack in groups.

Easy "Vaporize" achievement

You must kill five enemies with a dropped enemy grenade to get the "Vaporize" achievement. In Chapter 3, reach the second checkpoint (the second time you are dropped from the car) on the easiest difficulty. Stand by the door, and wait for one of the soldiers to throw a grenade at you, then shoot him until he dies or drops the grenade. Keep restarting from the checkpoint until you manage to kill all the soldiers with the dropped enemy grenade to get the achievement.

Achievements

Accomplish the indicated achievement to get the corresponding number of Gamerscore points:

Gunner (20 points): Save allied planes.

Fergus saved (30 points): Choose to save Fergus.

Wyatt saved (30 points): Choose to save Wyatt.

Vive la resistance! (20 points): Locate the resistance.

Power to the laser (30 points): Find the Laserkraftwerk.

Hidden in the deep (20 points): Locate the underwater stash.

London uprising (20 points): Defeat the London Monitor.

Deliverance (30 points): Release friend.

Liberation (100 points): Complete the game on any difficulty.

Super hero (50 points): Complete game on I AM DEATH INCARNATE! (or ÜBER).